That is why it is MINIMUM. We all know that multi-ton masses cannot float in the air.

That is why it can only be simulated in a computer. Is something stopping you from making and explaining a computer model that can fall from a
simulated 1360 feet and come down in less than 12 seconds. Free fall of a single mass takes 9.2 seconds which is not even a collapse so I have no
idea what you can possible come up with.

3- you claim that more ke is "consumed" accelerating each level than what reality shows : no ext columns were accelerated. no ke "consumed" there.
Nor is any ke "consumed" breaking their connections since gravity/tilting is "free". Few core columns were accelerated either. Nor is any ke
"consumed" breaking their connections. And for both ext and core columns, no ke would be "consumed" buckling them since they were not buckled
during the collapse progression.

The only things that "consume" ke is: breaking floor to column connections, and you have that number. And accelerating the floors themselves, and
you used Greg's number for that.

I would love to see a good model of a collapse of a structure very much like a WTC tower. How can anyone build one if they don't have accurate data
of the building. Why aren't all of the believers in collapse demanding that data? I don't even know the true weight of a floor assembly. The
concrete should be 600 tons but how much did the floor pans and trusses weigh? So you complain about my modeling while not demanding information to
do really good modeling.

The point is we are talking about structures with MULTIPLE LEVELS and ENERGY is required to crush each LEVEL. That is why paper loops are crushed in
my drop demonstration. But the amount of energy used up crushing those 9 paper loops is the same as the Potential Energy of the empty space that the
dropped mass falls through.

If you read that link and put your brain in gear you will notice no mention of Newton's 3rd Law and the falling 30 stories do not themselves get
crushed in the process of crushing the floors below. But that happens in my physical model. He also says nothing about the lower stories being
stronger and heavier than the levels above.

There is also the matter of the top 30 stories tilting 22 degrees. Where was the center of mass? Why didn't it tilt further and fall down the side.
It is so curious how PARTIAL ANALYSIS with a little math can encourage one belief but complete analysis does not even get done in ten years. What is
so difficult about discussing the center of mass of the top of the south tower?

Dave whatisname seems to forget about equal opposite reaction. He seems to forget the fact that all the force of the dynamic loading is still felt
equally by both colliding floors. He seems to not realise that the force of all the falling floors would effect more than just the one impacted
floor, an equal amount of force would be absorbed by both impacting floors. He also ignored the loss of Ke to deformation, sound, heat etc.

The biggest fail though is if it was simply pancaking floors adding mass, there would have been a stack of floors in the footprint. You can't have it
both ways, if there were no stack of floors they were obvioulsy removed during the collapse, which means there was no mass to increase.

But his paper forgets that for that to all have happened in the first place trusses all had to have sagged and pulled in columns causing them to fail,
allowing the whole top section to fall as one. He does not explain how sagging trusses can put a pulling force on the columns. The most important
part of the NIST report gets treated like it's a given, yet no one can demonstrate this phenomena.

He should try his pennies and paper experiment with more realistic conditions like pennies dropping on pennies.

Dave also didn't study the collapses very well, you can see the top section is collapsing bottom up before the bottom section even moves...

Why do you need Dave or Bazant to tell you what to think? Can't you see that the tower is not acting in the way either of them claim? Why is the
insistence that I review what these people say going to change anything? I don't ask you to write reviews of other peoples work. But thank you
though, now I know where you get the "dynamic loading" nonsense from. More proof that you all fail to understand the details needed to understand
what happened by yourself. Another of your hand-holders exposed lol.

The biggest fail though is if it was simply pancaking floors adding mass, there would have been a stack of floors in the footprint. You can't have
it both ways, if there were no stack of floors they were obvioulsy removed during the collapse, which means there was no mass to increase.

But if all the floors were ejected during the explosions shouldn't there be a big empty hole were the towers once stood ?

Dave whatisname seems to forget about equal opposite reaction. He seems to forget the fact that all the force of the dynamic loading is still felt
equally by both colliding floors. He seems to not realise that the force of all the falling floors would effect more than just the one impacted
floor, an equal amount of force would be absorbed by both impacting floors. He also ignored the loss of Ke to deformation, sound, heat etc.

RIght right right, equal and opposite, blah blah blah, its a shame you do not understand how this works in the real world. Fact is: Equal and
opposite only refers to the force experienced by both objects at the same time. ie, pushing on a wall and the wall pushes back or standing on the
ground and the ground is pushing up with the same amount of force. THAT is what "equal and opposite" means. It has NOTHING to do with what
physically happens ANOK. This is BASIC physics 101. I thought you knew that. Also, it was not one floor on one floor, but 25+ floors on one floor,
then 26 floors vs one floor, then 27 floors vs one floor, etc etc etc. Chain reaction ANOK. Mass increased, constant acceleration, all overcame each
floor's attachments to the columns.

The biggest fail though is if it was simply pancaking floors adding mass, there would have been a stack of floors in the footprint. You can't have
it both ways, if there were no stack of floors they were obvioulsy removed during the collapse, which means there was no mass to increase.

Oh ANOK, its almost been a year since I asked you to provide ANY evidence of the majority of the mass being ejected outside the footprint. Nearly a
whole year. I didn't believe it could take so long, but hey, I can wait. So when can I expect to see actual evidence of entire floor sections being
ejected outside the footprint? You know I asked it before, any evidence will do. Pictures, video, eyewitness accounts. Hell I will settle for a
piece of floor truss with a small attachment of the corrugated steel pan, and a slab of concrete found 50ft from the footprint of either WTC. Or even
one whole truss outside the footprint. Please ANOK? I've been very patient with you on this.

Dave also didn't study the collapses very well, you can see the top section is collapsing bottom up before the bottom section even moves...

Neat gif. However, ANOK, if you recall, the columns bent inwards prior to collapse. The top section fell behind the bottom sections exterior
columns, like a plunger, forcing out the exterior columns and helping sever the truss connections and having the floors come down all together.

I am in the process of making a reply to ANOK's BS which I will post later maybe if you did some time actually on a multi storey building this
wouldn't be such a mystery to you armchair builders. Of out now to work guess where

I am in the process of making a reply to ANOK's BS which I will post later maybe if you did some time actually on a multi storey building this
wouldn't be such a mystery to you armchair builders. Of out now to work guess where

edit on 21-6-2012 by wmd_2008 because: (no reason
given)

What do people mean by FLOORS?

Do they mean the same thing as STORIES?

Are they talking about the FLOORS outside the cores of the WTC?

The washers in my physical model are simply MASS as far as I am concerned. But since mass has WEIGHT it must be supported against GRAVITY.

Now the paper loops in my physical model perform the same FUNCTION as the COLUMNS in the WTC. But my model is not a tube-in-tube structure. There
were about 200 connections around the inner and outer edges of each FLOOR of the WTC. But how strong were they relative to the weight of the FLOOR
ASSEMBLY. I don't know. I have never even seen the total weight of the FLOOR ASSEMBLY specified.

As far as I can tell most people think in terms of what they see. I think that is dumb but they do it anyway. My washers are round and flat and in
horizontal positions so most people regard them as similar to the FLOORS in the WTC. But those FLOORS do not include the mass in the core and the
perimeter columns.

I could have built a model using a clear plastic tube with big ball bearings for mass and still used paper loops to separate the steel balls. I would
probably have to drill holes to let air out to keep air pressure from affecting the collapse. Then the dummies would not confuse the spherical masses
with FLOORS in the WTC. But it would be more expensive and difficult to use than what I built.

My model is of a gravitational collapse of a self supporting structure. I am attempting to demonstrate and explain the physics of such a collapse
which is what many people claim happened to the WTC. Obviously a gravitational collapse in a true tube-in-tube structure would be somewhat more
complicated but the conservation of momentum is not going to disappear because of that. But why doesn't everybody want accurate data on the WTC so
an engineering school with more resources than me can build a good physical model and test it? But if people at those engineering schools know it
would not collapse then they have a problem. They would have to explain why they didn't tell everybody that TEN YEARS ago.

Breaking those connections would still require energy and slow the collapse down. How could the north tower come down in less than 26 seconds? How
can this be analysed without accurate distribution of steel and concrete data? Why haven't all of the engineering schools been demanding it for TEN
YEARS? Less than 26 seconds is still more than 1/3rd of free fall acceleration. That is ridiculous for a building that held itself up for 28 years
and withstood 100 mph winds on several occasions. It is especially ridiculous for the nation that put men on the Moon to not have explained it in TEN
YEARS.

Considering that there are 200 buildings around the world over 800 feet tall and gravity is pretty much the same all over the planet, 9/11 is an
international issue. Are other governments refusing to tell the entire world that the United States government is lying? Physics does not give a
damn about politics or religion. And if it is really easy to understand what skyscrapers that big cannot collapse that fast then a lot of people
would have to admit they have been really stupid for ten years.

Isaac Newton was a Brit. He is an intellectual hero to Western Culture. How does all of Western culture explain getting this wrong for TEN YEARS?
Or is everybody supposed to be stupid and think whatever Western Culture tells them. Wouldn't this mean that most people of European descent think
whatever authority tells them no matter how DUMB it is and all of this debate is just rhetorical crap like angels on the head of a pin?

There is rubble about the height of two stories, but no stack of floors is there?

Floors pancaking would not have the energy to both break connections, and cause all the steel floor pans and concrete to simply turn into rubble.
There would have been a stack of floors, not a pile of rubble of few feet high.

You cannot explain where all the energy came from to both cause the collapse to accelerate against resistance, and turn the floor assemblies into
rubble.

This is what a pancake collapse looks like, because there is not going to be enough energy to break the floors into rubble....

We all know the rubble was ejected in 360d arc around the towers, the majority of the mass did not stay in the footprint. Funny how you insist it
did, yet when talking about WTC 7, that obvioulsy did land mostly in it's footprint you deny it, that to me stinks of dishonesty.

But forget that, when are you going to explain how sagging trusses can put a pulling force on the columns? When are you going to put your money where
your mouth is and demonstrate this phenomena? Catenary action is demonstrated here, and it fails to pull in columns. Columns much weaker than the
WTC, floors that have weight added, unlike the WTC, and core columns removed, unlike the WTC.

Surely if you understand physics and engineering as you claim, you can see if that phenomena doesn't work for this building it wouldn't work for the
towers?

Originally posted by ANOK
I back up everything I say with real world physics, all you can provide is papers directly related to covering up the real reason the buildings
collapsed.

Yes Anok - All the authors of the papers and conferences etc. etc... are all covering up the "real" reason. Only YOU have it right....

Let's look at who's "covering up"

A Bibliography Of Scientific Literature On The World Trade Center Collapse

Studies And Investigations

2002/05 - Federal Emergency Management Agency (FEMA) and the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE) -
World Trade Center Building Performance Study -
2002/05 - Massachusetts Institute of Technology (MIT) - The Towers Lost and Beyond
2002/09 - John D. Osteraas - World Trade Center: Assessment of Structural and Architectural Damage; The study was conducted for Exponent Failure
Analysis Associates on behalf of Swiss Re and other insurers of the WTC complex.
2002/09 - Ali Reza - Damage to the WTC Complex Due to the Collapse of Only One Tower; The study was conducted for Exponent Failure Analysis Associates
on behalf of Swiss Re and other insurers of the WTC complex.
2002/10 - Weidlinger Associates Inc. (WAI), LZA Technology/Thornton-Tomasetti, ARUPFire, Hughes Associates Inc., Hillman Environmental Group, RWDI,
Z-Axis Corp - World Trade Center - Structural Engineering Investigation - link; The study was performed by a group of engineering firms led by WAI and
was conducted on behalf of Silverstein Properties.
2005/09 - National Institute of Standards and Technology (NIST) - Federal Building and Fire Safety Investigation of the World Trade Center Disaster -
link
2006/09, 2007/04 - Purdue University, Computer Graphics and Visualization Lab - High-Fidelity Visualization of Large-Scale Simulations -

Articles by and about the tower engineers and investigators, progressive collapse info, engineering resources
Main 9/11 Links Page

"I am disgusted, disgusted with the structural engineers who know the truth about this and are keeping their mouth shut. There’s a special place in
Hell reserved for them. And they are going to deserve it." -"Scholar for 9/11 Truth" James Fetzer

See also: Fire Safety Engineering & the Performance of Structural Steel in Fires

NIST Final Reports on WTC 1 & 2
NIST NCSTAR 1 (PDF): URL="http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR%201.pdf"]Federal Building and Fire Safety Investigation of the World Trade Center
Disaster: Final Report of the National Construction Safety Team on the Collapses of the World Trade Center Towers[/url]

Journal and Conference Papers
Peer-reviewed papers and conference papers about the WTC impacts, fires, and collapses

WTC collapse papers with Zdenek Bazant as lead author
What Did and Did not Cause Collapse of WTC Twin Towers in New York Authors Bazant, Le, Greening & Benson. Journal of Engineering Mechanics ASCE 134
(2008). Refutation of controlled demolition theory. Discusses matching of video record with progressive collapse equations, "free-fall" claims,
concrete crushing (and how much TNT equivalent would be needed to do that crushing), air pressure & ejection of air, spread of dust cloud.
Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions Co-author Verdure. PDF. Journal of Engineering Mechanics
ASCE 133 (2007): pp. 308-319
Excerpt (applies to link above and below): The kinetic energy of the top part of the tower impacting the floor below was found to be about 8.4x larger
than the plastic energy absorption capability of the underlying story, and considerably higher than that if fracturing were taken into account
(Ba=C5=BEant and Zhou 2002a). This fact, along with the fact that during the progressive collapse of underlying stories the loss of gravitational
potential per story is much greater than the energy dissipated per story, was sufficient for Ba=C5=BEant and Zhou (2002a) to conclude, purely on
energy grounds, that the tower was doomed once the top part of the tower dropped through the height of one story (or even 0.5 m).
Discussion and replies to June 2006 Bazant & Verdure paper: James Gourley, G. Szuladinski. Closing comments from Bazant to Gourley (after detailed
rebuttal to his claims):
Although everyone is certainly entitled to express his or her opinion on any issue of concern, interested critics should realize that, to help discern
the truth about an engineering problem such as the WTC collapse, it is necessary to become acquainted with the relevant material from an appropriate
textbook on structural mechanics. Otherwise critics run the risk of misleading and wrongly influencing the public with incorrect information.
Bazant & Zhou, 2001-2002: Why Did the World Trade Center Collapse? - Simple Analysis J. Engineering Mechanics ASCE, Sept. 28, 2001, addendum March,
2002.

Why didn't the towers, or the upper portions of them, topple over?
Why didn't the upper part pivot about it's base? See Bazant & Zhou (2001) Appendix II
Eduardo Kausel (MIT): Why the Towers didn't fall like trees
Frank Greening: An analysis of the tipping of the upper section of WTC 2 (PDF)
A simple graphic explanation of why the top of the south tower didn't fall to the side.
Physicist Dave Rogers on tipping of tower tops.
Structural engineer "Newton's Bit" on "tipping"

There are plenty of others... I dont want to be accused of "spamming" with facts.

Floors pancaking would not have the energy to both break connections, and cause all the steel floor pans and concrete to simply turn into rubble.
There would have been a stack of floors, not a pile of rubble of few feet high.

Anok seriously, you really need to do some real research on building materials and how the materials function as a whole.

Your lack of knowledge on construction materials and the intended uses shows in your posts.

Concrete crumbles and steel twists and shears. Metal decking is usually as thin as 1/8 to 3/16 inch thick, sometimes thinner. 4 inches of concrete
cracks easily under normal stresses. Trusses are only designed for a certain amount of weight and stress.

Each of these items were subjected to stresses and forces way outside their intended specifications. A simple understanding of construction methods
and materials would be all it takes for someone to understand this.

Can you demonstrate sagging trusses putting a pulling force on the columns?

Heat caused steel in the floor trusses to expand, promoting buckling in columns, at the same time that the heat softened the steel and the
aircraft debris contributed to gravity loads, leading to progressive collapse.

Did you forget about the 300,000 to 400,000 pounds of plane weight that was instantly subjected to the floor trusses?

The third event was a progressive collapse: "As the large mass of the collapsing floors above accelerated and impacted on the floors below, it
caused an immediate progressive series of floor failures, punching each in turn onto the floor below, accelerating as the sequence progressed.
Freestanding exterior walls... buckled at the bolted column splice connections and also collapsed."

After the initial impacts, the most heavily loaded columns were probably near, but not over, their ultimate capacities. The structure successfully
redistributed the building weight to the remaining elements and maintained stability long enough for a life-saving evacuation.

It seems by the explanation above that right after the impacts the stress was distibuted enough to withstand the stresses for a while.( I noticed it
said probably) Until the connections were fatigued(by added weight and loss of strength due to fire) enough to where they couldn't handle the added
loads anymore. Notice it said maintained stability long enough for evacuation. Which in turn means that after a while the structure could not handle
the stresses anymore.

Remember that the exterior columns were connected with bolts. Bolts have something called shear strength.

Shear strength in engineering is a term used to describe the strength of a material or component against the type of yield or structural failure
where the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is
parallel to the direction of the force. When a paper is cut with scissors, the paper fails in shear.

What is wrong with the progressive collapse explanation? I see that you are probably going to go with the "their in on the cover up" explanation. I
feel that architecture week is a pretty credible source.

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